1. Field of the Invention
The present invention relates to methods for treating, reducing or preventing one or more symptoms or adverse effects of a herpes infection and to methods for reducing the infectivity or transmission of herpes infections.
2. Description of the Related Technology
Viral pathogenesis is the method by which viruses produce disease in the host. The pathogenesis of viruses centers on the mechanisms of viral injury to discrete populations of cells in particular organs to produce signs and symptoms of disease in a particular host.
To initiate an infection the virus must gain entry to the host cell. Entry routes are dependent on the virus and include the skin, eyes, respiratory, GI and urogenital tracts as well as the circulatory system. Some viruses localize their tissue injury in close proximity to their site of entry, particularly the viruses that infect the upper respiratory tract such as influenza, parainfluenza, rhinoviruses and coronavirus. Once the viral particle has invaded the cell, viral coded proteins direct the cell to replicate the viral genome and produce viral specific proteins. These proteins are assembled into complete virions along with the viral genome and released. In the case of enveloped viruses, the virions acquire a lipid membrane and will insert through this lipid membrane, viral specific glycoproteins. The enveloped virus families include the Herpesviridae, Retroviridae, Orthomyxoviridae, Paramyxoviridae, Flaviviridae, Togaviridae and Coronaviridae. The rhinoviruses are members of the Picornaviridae, which are not enveloped.
Viruses have evolved a number of mechanisms to enter a host cell and initiate infection. To fuse to the cell membrane, viruses have a membrane glycoprotein with membrane fusion activity. Many enveloped virus induce a receptor-mediated endocytosis after binding to the cell surface receptor, causing the cell to form an endosomal vesicle. Once inside the vesicle, the virus particle undergoes the uncoating process. This insures that the optimal pH for the viral genome is maintained and that the viral genome is protected from cellular nucleases.
Ocular herpes is a recurrent viral infection that is caused by the herpes simplex virus and is the most common infectious cause of corneal blindness. There are two types of herpes simplex viruses. HSV-1 primarily infects the mouth, face and eyes. HSV-2 primarily causes genital infections. However, either HSV-1 or HSV-2 can manifest itself as an ocular disease.
Ocular herpes can produce painful sores on the eyelids or surface of the eye and may cause inflammation of the cornea. Prompt treatment with anti-viral drugs helps to stop the herpes virus from multiplying and destroying epithelial cells. However, the infection may spread deeper into the cornea and develop into a more severe infection called stromal keratitis, which causes the immune system to attack and destroy stromal cells.
Like other herpes infections, ocular herpes can be controlled but not cured. An estimated 400,000 Americans have had some form of ocular herpes. Topical antiviral treatment of ocular herpes is available, but the most frequently used topical agent can be toxic to the corneal epithelium. Thus, there is a need for a safe, topical virucidal agent that can eliminate the virus in initial or recurring episodes and than can inhibit ocular herpes outbreaks due to contact lenses, drugs and cosmetics coming into contact with the cornea.
Genital herpes is an infection of the genitals, buttocks or anal area caused by the herpes simplex virus (HSV). HSV-2 is most commonly associated with genital herpes, though HSV-1 may cause up to about 10% of cases of genital herpes. HSV-2 can also infect the mouth. According to the Centers for Disease Control and Prevention, 1 out of 5 American teenagers and adults are infected with HSV-2. Medicines available to treat genital herpes include acyclovir, famciclovir and valacyclovir. However, there remains a need for alternative medicines for treatment of genital herpes.
Therefore, there exists a need in the field to provide a prophylactic method for the reduction of the incidence of contracting an illness caused by a microbial organism.